While equipment cost and luxury features may limit energy savings on portable spas, manufacturers nonetheless are exploring more energy-efficient designs.

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Hydraulic design and filtration also have played a role in improved
efficiency.

A portable spa
decked out with hundreds of jets, an 80,000-BTU electric heater and
a surround-sound LCD flat screen doesn’t exactly yell
green.

Yet some of the most impressive improvements in energy efficiency
have also come from manufacturers. Better insulation and equipment
help conserve power, and sophisticated control systems can
micromanage running times.

Cost is still a prohibitive factor, but as energy prices rise, spa
designs will continue to get greener.

Insulation

Not surprisingly, the most critical element in saving energy in
portable spas is heat retention. Given that nearly 75 percent of
heat loss often can be attributed to evaporation, covers are
crucial to the energy efficiency of hot tubs.

“The overwhelming majority of the industry uses a similar
type of cover construction — it’s vinyl-clad with an
EPS (encapsulated polystyrene) core,” notes Sam Collins, vice
president of operations for Marquis Spas in Independence, Ore.

These covers prevent the vast amount of potential heat loss.
However, they are still subject to moisture damage, as water seeps
in and lowers the product’s R-value, or ability to retain
heat. As such, manufacturers developed a vapor barrier wrap to
prolong the life of the cover’s insulation.

The actual design of the cover also has become more important.
Every crack or joint that exposes the heat to the open air
drastically accelerates heat loss.

The physical insulation within the spa also has undergone
improvements.

“We’ve seen a lot of change in insulation to blanket
wraps, to foam insulation in the frame work, on the floor, and even
some materials that aren’t as much traditional insulation
materials, but more of a hybrid that would go in there,” says
Brian Wiley, president of Premium Leisure in St. Petersburg, Fla.

The frame itself is now almost always supplemented with a hard
bottom cover, which protects against both heat loss and permeation
from outside elements, namely rain.

Being green has become an important marketing tool in selling
portable spas. This is not just in saving energy through
insulation, but also by advertising recyclable materials. Companies
push hybrid materials to accent various styles.

Equipment round-up

Improved equipment has also been a key to energy-efficiency among
portable spas. The single largest advance is in the motor
efficiency and design of pumps. (Click here to see how filtration and hydraulics
have helped improve efficiency.)

Many portable spas use separate pumps to operate the jets and
filtration, allowing minimal energy usage for the latter.

“I’ve seen a change to more circulation pumps,”
Wiley notes. “There’s a cost factor, but they’re
made to require a lot less energy.”

Manufacturers who stand behind a single pump design utilize a large
two-speed model, which is designed to run only during
operation.

Some companies are even experimenting with variable-speed
technology. These pumps allow minimal energy usage during normal
filtration cycles. They can also be optimized to control the amount
of amps used for different jet speeds.

However, because of the cost, portable spas with this technology
are only available in high-end models, limiting their growth in the
current economy.

“Where the market is today is geared toward mid-priced
products,” Wiley says. “But I think it will grow when
the market comes back.”

Variable-speed pumps have the additional benefit of allowing users
to choose their massage settings. Presets can even be arranged for
varying jet pressures during a single run.

The heater, however, remains a major source of energy consumption
with no obvious solution. Electric models are the most convenient
and least expensive products to buy. And even with operational
savings, other styles of heaters just don’t make sense.

“We’re trying to provide a product as a manufacturer to
anyone and everyone,” Collins notes. “Not everyone has
… access to geothermal heat or solar heat on the
roof.”

Mission control

Although typically associated with convenience, new control systems
allow a more efficient distribution of energy usage across the hot
tub.

“One of the bigger opportunities lies in the equipment and
how the equipment is configured,” Collins says. “The
changes in the last 10-15 years have been the advent of electronic
controls, being able to configure the software.”

User-friendly software allows homeowners to program filter cycles,
clean-up cycles and heater cycles. In an area where energy costs
are higher during the day, because that’s when the main load
is, you can program your spa to switch on and filter at night when
the rate isn’t as high.

Controlling the pump has also paid major dividends. While some
models are set to run all the time, the control system will
actually moderate the pump use according to temperature. The
circulation pump won’t run until it reaches 3 degrees under
or over the set point.

“I think some of your energy savings are from the computers
being smart enough to change the programming depending on your
usage,” Wiley says.

While spa owners often prioritize comfort ahead of energy savings,
the equipment and software are there for more green-conscious
homeowners.